In agriculture, it is common to perform work operations in fields which contain crops by using tractors and other mobile machines. In these circumstances, care must be taken to avoid unwanted contact with the crops to prevent crop damage from occurring. For example, it is often required to loosen hardened soil between rows of crops to promote proper drainage of water in the fields by pulling a ripping apparatus through the soil adjacent the plants. However, care must be taken to avoid contact with the plants by the ripping apparatus.
Historically, farmers avoid inflicting damage to crops as much as possible by visually observing the locations of the rows of crops as the fields are traversed. However, over a period of time, it becomes more difficult to avoid contact with the crops as the farmers become fatigued. Additionally, it is sometimes difficult to maintain good visual contact with the rows.
The problem is much more difficult in certain situations where the crop may exist only under the surface of the earth as root balls. For example, sugar cane farming is based on leaving the root balls in the earth after harvest to grow into the next season's crop. During the time in which only root balls exist in the field, farmers may need to traverse the field to install irrigation drip lines, or to loosen hardpan, i.e., the hardened soil under the root balls. In these circumstances, the farmer has no view of the crop, and must rely on guessing the locations of the rows of root balls to avoid damaging the crop or wait until a new crop begins to grow.
Attempts have been made to determine the location of crops during initial passes over a field through the use of position determining methods such as global positioning satellite (GPS) systems, and storing this information in a database for subsequent use. For example, in U.S. Pat. No. 5,438,817, Nakamura discloses a system in which GPS stores in a database the location of rice plants growing in a rice field. The database is then used to determine the route to be traversed by a reaper.
However, in systems such as these, accuracy within several centimeters must often be maintained. Typical position determining systems cannot guarantee this type of accuracy throughout an entire field. In addition, if the initial database is not accurately created, the error will repeat every time machines enter the field.
Furthermore, maintaining and using a database of the locations of the crop adds cost and complexity to the overall system. It is often desired to detect the locations of the crop in real time using an accurate and economical detection means.
The present invention is directed to overcoming one or more of the problems as set forth above.